Blogs

Agility@Scale: Strategies for Scaling Agile Software Development

Scott is a Senior Consulting Partner of Scott W. Ambler and Associates, working with organizations around the world to help them to improve their software processes. He provides training, coaching, and mentoring in disciplined agile and lean strategies at both the project and organizational level. He is the founder of the Agile Modeling (AM), Agile Data (AD), Disciplined Agile Delivery (DAD), and Enterprise Unified Process (EUP) methodologies. Scott is the (co-)author of 19 books, including Disciplined Agile Delivery, Refactoring Databases, Agile Modeling, Agile Database Techniques, The Object Primer 3rd Edition, and The Enterprise Unified Process. Scott is a senior contributing editor with Dr. Dobb's Journal and his company home page is ScottWAmbler.com

I've been getting a lot of questions lately about applying the acceleration metric in practice. So, here's some answers to frequently asked questions:1. How do I monetize acceleration? This is fairly straightforward to do. For example, assume your acceleration is 0.007 (0.7%), there are five people on the team, your annual burdened cost per person is $150,000, and you have two week iterations. All these numbers are made up, but you know how to calculate acceleration now and IT management had darn well better know the average burdened cost (salary plus overhead) of their staff. So, per iteration the average burdened cost per person must be $150,000/26 = $5,770. Productivity improvement per iteration for this team must be $5,770 * 5 * .007 = $202. If the acceleration stayed constant at 0.7% the overall productivity improvement for the year would be (1.007)^26 (assuming the team works all 52 weeks of the year) which would be 1.198 or 19.8%. This would be a savings of $148,500 (pretty much the equivalent of one new person). Of course a 20% productivity increase over an entire year is a really aggressive improvement, regardless of some of the claims made by the agile snake oil salesman out there, although at 10-15% increase is a reasonable expectation. What I'd really want to do is calculate the acceleration for the year by comparing the velocity from the beginning of the year to the end of the year (in Western cultures I'd want to avoid comparing iterations near to the holidays). So, if the team velocity the first week of February 2008 was 20 points, now the same team's velocity the first week of February 2009 was 23 points, that's an acceleration of (23-20)/20 = 15% over a one year period, for a savings of $112,500.2. Is acceleration really unitless? For the sake of comparison it is. The "units" are % change in points per iteration, or % change in points per time period depending on the way that you want to look at it. Because it's a percentage I can easily monetize it, as you see above, and use it as a basis of comparison. 3. How do I convince teams to share their data? This can be difficult. Because acceleration is easy to calculate for agile teams, and because it's easy to use to compare teams (my team has .7% acceleration whereas other teams down the hall from mine have accelerations of .3% and -.2% of teams), people are concerned that this metric will be used against them. OK, to be fair, my team might be OK with this. ;-) Seriously though, this is a valid fear that will only be addressed by an effective governance program based on enablement, collaboration, and trust instead of the traditional command-and-control approach. Management's track record regarding how they've used measurements in the past, and how they've governed in general, have a great effect on people's willingness to trust them with new metrics such as acceleration. The implication is that you need to build up trust, something that could take years if it's possible at all.4. Why does this work for agile teams? Agile teams are self organizing, and an implication of that is that they will be held accountable for their estimates. Because of this accountability, and because velocity is a vital input into their planning and estimation efforts, agile teams are motivated to calculate their velocity accurately and to track it over time. Because they're eager to get their velocity right, and because acceleration is based on velocity, there's an exceptionally good chance that it's accurate.5. What about function points or similar productivity measures? Function points can be calculated for projects being developed via an agile approach, or other approaches for that matter, but it's a very expensive endeavor compared to calculating acceleration (which is essentially free) and likely will be seen as a bureaucratic overhead by the development team. My rule of thumb is that if you're not being explicitly paid to count function points (for example the US DoD will often pay contracting companies to create estimates based on function point counts) then I wouldn't bother with them.6. What about calculating acceleration for iterative project teams? Iterative project teams, perhaps following Rational Unified Process (RUP), can choose to calculate and track their velocity and thereby their acceleration. The key is to allow the team to be self organizing and accountable for their estimates, which in turn motivates them to get their velocity right just like agile teams (RUP can be as agile as you want to make it, don't let anyone tell you differently).7. What about calculating acceleration for traditional project teams? In theory this should work, in practice it is incredibly unlikely. Traditional teams don't work in iterations where working software is produced on a regular basis, they're typically not self organizing, and therefore there really isn't any motivate to calculate velocity (even if they do, there is little motivation to get it right). Without knowing the velocity you can't calculate acceleration. If you can't trust the velocity estimate, and I certainly wouldn't trust a traditional team's velocity estimate, then you can't trust your acceleration calculation. So, my fall back position to calculate productivity improvement would be to do something like function point counting (which is expensive and difficult to compare between teams due to different fudge factors used by different FP counters) and then looking at change in FPs delivered over time.8. How can I apply this across a department? It is fairly straightforward to roll up the acceleration of project teams into an overall acceleration measure for a portfolio of teams simply by taking a weighted average based on team size. However, this is only applicable to teams that are in a position to report an accurate acceleration (the agile and iterative teams) and of course are willing to do so.9. What does a negative acceleration tell me? If the acceleration is negative then productivity on the team is going down, likely an indicator of quality and/or team work problems. However, you don't want to manage by the numbers so you should talk to the team to see what's actually going on.10. What does a zero acceleration tell me? This is an indication that the team's productivity is not increasing, and that perhaps they should consider doing retrospectives at the end of each iteration and then acting on the results from those retrospectives. Better yet they can "dial up" their process improvement efforts by adopting something along the lines of IBM Rational Self Check.Further reading:

A common goal of IT governance is to determine the productivity of various techniques, tools, and people as part of the overall effort to improve said productivity. If you can easily measure productivity you can easily identify what is working for you in given situations, or what is not working for you, and adjust accordingly. A common question that customers ask me is how do you measure productivity on agile teams. Although you could use traditional strategies such as function point (FP) counting, or another similar strategy, this can require a lot of effort in practice. Remember that we don't only want to measure productivity, we want to do so easily. Ideally it would be nice to do so using information already being generated by the team and therefore we won't add any additional bureaucratic overhead.

A common metric captured by agile teams is their velocity. Velocity is an agile measure of how much work a team can do during a given iteration. At the beginning of an iteration a team will estimate the work that they're about to do in terms of points. At the beginning of a project the team will formulate a point system, which typically takes a few iterations to stabilize, so that they can consistently estimate the work each iteration. Although the point system is arbitrary, my team might estimate that a given work item is two points worth of effort whereas your team might think that it's seven points of effort, the important thing is that it's consistent. So if there is another work item requiring similar effort, my team should estimate that it's two points and your team seven points. With a consistent point system in place, each team can accurately estimate the amount of work that they can do in the current iteration by assuming that they can achieve the same amount of work as last iteration (an XP concept called "yesterday's weather"). So, if my team delivered 27 points of functionality last iteration we would reasonably assume that we can do the same this iteration.

So, is it possible to use velocity as a measure of productivity? The answer is not directly. For example, we have two teams, A and B, each of 5 people and each working on a web site and each having two-week long iterations. Team A reports a velocity of 17 points for their current iteration and team B a velocity of 51 points. They're both comprised of 5 people, therefore team B must be three times (51/17) as productive as team A. No! You can't compare the velocity of the two teams because they're measuring in different units. Team A is reporting in their points and B in their points, so you can't compare them directly, The traditional strategy would be to ask the teams to use the same unit of points, which might be a viable strategy with two teams although likely not if you have twenty agile teams and particularly not if you have two hundred teams. Regardless of the number of teams that you have it would minimally require some coordination to normalize the units and perhaps even some training and development and support of velocity calculation guidelines. Sounds like unnecessary bureaucracy that I would prefer to avoid. Worse yet, so-called "consistent" measurements such as FPs are anything but because there's always some sort of fudge factor involved in the process which will vary by individual estimator.

An easier solution exists. Instead of comparing velocities you instead calculate the acceleration of each team. For example, consider the reported velocities of each team below. Team A's velocity is increasing over time whereas team B's velocity is trending downwards. All things being equal, you can assume that team A's productivity is increasing whereas B's is decreasing. Of course it's not wise to manage simply by the numbers, so instead of assuming what is going on I would rather go and talk with the people on the two teams. Doing so I might find out that team A has adopted quality-oriented practices such as continuous integration and static code analysis which team B has not, indicating that I might want to help team B adopt these practices and hopefully increase their productivity.

There are several advantages to using acceleration as an indicator of productivity over traditional techniques such as FP counting:1. It's easy to calculate. For example, the acceleration of team A from iteration 1 to iteration 6 is (20-17)/17 = 0.176 whereas for team B it is (45-51)/51 = -.118. Of course, you don't need to calculate the acceleration over such a long period of time, you could do it iteration by iteration, although I find that doing it over several iterations gives a more accurate value. You'll need to experiment to determine what works for you.2. It is inexpensive. Acceleration is based on information already being collected by the team, their velocity, so there is no extra work to be done by the team. 3. It is unlikely to be gamed. Teams aren't motivated to fake their velocity because it provides them with important information required to manage themselves effectively. 4. It is easy to automate. For example, Rational Team Concert (RTC) calculates velocity automatically from its work item list (an extension of Scrum's product backlog) and does trend reporting via it's web-based project reporting functionality, providing a visual representation of the team's acceleration (or deceleration as the case may be).5. It offers the opportunity for more effective governance. This approach reflects three of the practices of Lean Development Governance: Simple and Relevant Metrics, Continuous Project Monitoring, and Integrated Lifecycle Environment.6. You can easily adjust for changing team size. If the size of a team varies over time, and it will, this metric falls apart the way that I've described it. To address this issue you need to normalize it by dividing by the number of people on the team to get the average acceleration per team member.7. You can easily monetize this metric. By knowing the acceleration of the project team and knowing how much they're spending each iteration, you can estimate the amount of money you're saving through process improvement. For example, if you're spending $100,000 per iteration and your acceleration is 2%, your cost savings is $2,000 per iteration.

Of course, nothing is perfect, and there are a few potential disadvantages:1. It is an indirect measure of productivity. Truth be told velocity really is a productivity measure, it's just that because it's measured in different units it's difficult to compare between teams. Acceleration is merely an indicator of the change in productivity.2. You actually need to measure what you're interested in. When you step back and think about it, you're not really interested in measuring your productivity, regardless of what the metrics wonks have been telling you the past few decades. In this case what you really want to know is your change in productivity because your real goal is to improve your productivity over time, which is what acceleration actually measures.3. Management must be flexible. For this to be acceptable senior management must be willing to think outside the "traditional metrics box". Using a non-standard, simple metric to calculate productivity? Preposterous! Directly measuring what you're truly interested in instead of calculating trends over long periods of time? Doubly preposterous!4. Your existing measurement program may be questioned. Once management learns how easy it can be to obtain metrics which enables them to truly govern software development projects they may begin to question the investment that they've made in the past in overly complex and expensive metrics schemes. This can be dangerous for the metrics professionals in your organization, particularly if your metrics group doesn't have valid measurements around the value of their own work. Ummmmm....5. The terminology sounds scientific. Terms such as velocity and acceleration can motivate some of us to start believing that we understand the "laws of IT physics", something which I doubt very highly that as an industry we understand. All it would take is for someone to start throwing around terms like "standard theory" and "unified model" and we'd really be in trouble. Wait a minute..... ;-)

In summary, measuring the acceleration of development teams is an easy to collect, straightforward measure of team productivity. I hope that I've given you some food for thought, and would be eager to hear about your experiences applying this metric in practice.